V4L/DVB (13907): cx18: Perform automatic rotation of very old, unread IDX buffers

[mv-sheeva.git] / drivers / media / video / cx18 / cx18-streams.c

diff --git a/drivers/media/video/cx18/cx18-streams.c b/drivers/media/video/cx18/cx18-streams.c
index 9755f4416e962f57be4ba308a46a2726ef7d9be9..680e7da5e5e48b48e88ae4c872f5c141463b4f00 100644 (file)
--- a/drivers/media/video/cx18/cx18-streams.c
+++ b/drivers/media/video/cx18/cx18-streams.c
@@ -463,6 +463,32 @@ static void cx18_vbi_setup(struct cx18_stream *s)
        cx18_api(cx, CX18_CPU_SET_RAW_VBI_PARAM, 6, data);
 }
 
+void cx18_stream_rotate_idx_mdls(struct cx18 *cx)
+{
+       struct cx18_stream *s = &cx->streams[CX18_ENC_STREAM_TYPE_IDX];
+       struct cx18_mdl *mdl;
+
+       if (!cx18_stream_enabled(s))
+               return;
+
+       /* Return if the firmware is not running low on MDLs */
+       if ((atomic_read(&s->q_free.depth) + atomic_read(&s->q_busy.depth)) >=
+                                           CX18_ENC_STREAM_TYPE_IDX_FW_MDL_MIN)
+               return;
+
+       /* Return if there are no MDLs to rotate back to the firmware */
+       if (atomic_read(&s->q_full.depth) < 2)
+               return;
+
+       /*
+        * Take the oldest IDX MDL still holding data, and discard its index
+        * entries by scheduling the MDL to go back to the firmware
+        */
+       mdl = cx18_dequeue(s, &s->q_full);
+       if (mdl != NULL)
+               cx18_enqueue(s, mdl, &s->q_free);
+}
+
 static
 struct cx18_queue *_cx18_stream_put_mdl_fw(struct cx18_stream *s,
                                           struct cx18_mdl *mdl)